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Ductless, Mini-split Heat Pumps

Field Test of Ductless Heat Pumps in Residences and Small, Commercial-Use Buildings

The purpose of this project is to evaluate the costs and benefits of ductless heating and cooling in several types of buildings. We have installed and are monitoring energy use by ductless heat pumps in several locations throughout the Pacific Northwest. This pilot study will investigate efficiency of ductless heating and cooling relative to other systems, including electric, forced-air furnaces. Through engineering analysis, we will also evaluate the coefficient of performance (COP) of cold-climate products in single-family and manufactured homes.

Applications examined in this work include:

  • Multi-family homes with zonal, electric heat
  • Manufactured homes with electric forced-air furnaces
  • Single-family homes with electric forced-air furnaces
  • Small, commercial-use buildings
  • Cold-climate ductless heat pumps in single-family and manufactured homes

Project Team
BPA: Kacie Bedney and Mark Johnson

2010 – 2012


Evaluation of Pilot Incentives Program for Ductless Heat Pumps in Single-Family Homes
Bonneville Power Administration, Northwest Energy Efficiency Alliance, and other electric utilities in the region have begun to implement a pilot incentive program http://www.nwductless.com/ with the goal of increasing use of high-efficiency, ductless heating and cooling systems in single-family homes. Called the Northwest Ductless Heat Pump Project, this initiative was launched in October 2008. The implementation phase of the pilot came to an end in December 2009, but project evaluation will continue through 2012. As of September, 2011, this pilot program has installed more than 11,000 qualifying ductless heat pumps in the Pacific Northwest. The Regional Technical Forum plans to evaluate data from this pilot program in 2012.

Other objectives of this pilot program include:

  • Demonstrating the use of inverter-driven ductless heat pumps to displace electric resistance space heat in existing Northwest homes
  • Supporting evaluation efforts to document project implementation and determine the costs and potential energy savings of ductless heat pumps in this application
  • Examining non-energy benefits and potential barriers to large scale implementation of ductless heat pumps
  • Building a regional infrastructure to sustain and accelerate market growth

This report on 2008 – 2009 implementation activities provides an overview of project highlights, key success, and lessons learned.

Project Team
BPA: Mark Johnson and Sarah F. Moore
NEEA: Anuradha Teja

2007 – 2012 (in progress)


Field Test of Ductless Heat Pumps in Single-Family Homes

Beginning in 2007, Bonneville Power Administration sponsored a small pilot project aimed at demonstrating the feasibility of ductless heat pumps for displacement of electricity demand by less efficient zonal electric space heating in single-family homes. Fourteen ductless heat pumps were installed in 2007 and early 2008 at locations in Oregon and Washington. Seven of the homes in Oregon were continuously monitored from early 2008 through September 2011.

The average, weather-normalized, decrease in energy use for home space heating at our 11 Monmouth sites was 4,200 kWh/year. This study also found that the seasonality of domestic hot water loads may be overestimated by the standard approach used in analysis of electricity bills. Billing analysis is improved substantially when bills are available over a three-year period. Supplemental space heating provided by 120V plug-in heaters can be significant. Cooling loads could negatively impact overall efficiency of heating and cooling. Direct metering of cooling equipment will allow this effect to be better quantified.

Project Team
BPA: Kacie Bedney, Adam Hadley, Jack Callahan, Mark Johnson, Sarah F. Moore

2007 – 2011 (in progress)


Laboratory Test of a Fujitsu Ductless Heat Pump

Because of the interaction between the compressor speed, the fan speed and the remote control, the actual performance of ductless heat pumps is difficult to assess. This project tested the performance of a variable-speed, Fujitsu ductless heat pump under laboratory conditions. As an alternative metric, this project measured heating and cooling efficiency versus outdoor temperature for both cooling and heating.

Overall, the performance of the Fujitsu ductless heat pump was remarkable during part-load operation. Our findings show the system performed better than manufacturer’s ratings. When the coefficient of performance was converted to Energy Efficiency Rating (EER) using a conversion factor, we found an EER of about 17. These results covered all operating conditions within 5°F of the outdoor temperature, the standard for EER evaluation used by U.S. Department of Energy.

Project Team
BPA: Kacie Bedney, Jack Callahan, Sarah F. Moore, Mark Johnson

2008 – 2009


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